1. Field of the Invention
The present invention relates to a parallelogram hinge for vertical-movement doors having a reduced bulkiness in depth at the inside of the piece of furniture.
2. State of the Prior Art
Commonly used are articulated-parallelogram hinges adapted to move doors in a vertical direction with combined translation and rotation movements so as to fully clear the access opening to the inside of the piece of furniture. Due to their features, these opening systems are currently used for tall pieces of furniture, such as kitchen wall cupboards, for example.
To balance the door weight during movement, gas springs are currently used, these springs being preferred to the helical springs because they enable quite higher loads, the sizes being the same.
The configuration normally used is that shown in FIG. 1 where a known parallelogram hinge is represented, being generally denoted at 10, in an open position (in chain line the closed position is partly shown). The gas spring 11, pivotally mounted on the fixed plate 13 at 12, exerts pressure on pin 14 that is integral with lever 15. In this manner, the dead centre positioned near the door closure being overcome, the whole mechanism consisting of levers 15 and 16 pivotally mounted on the movable plate 17 integral with door 18, is pushed in the opening direction. If the spring force is calculated in a correct manner, a balancing effect of the door weight is obtained which enables opening of said door to be controlled with a minimum effort.
All known mechanisms use gas springs mounted as shown in FIG. 1, i.e. with thrust axis substantially perpendicular to the plane of the closed door.
The main advantage offered by this choice consists in the possibility of only partly superposing the gas spring over the levers constituting the kinematic mechanism. Levers 15 and 16 lie in the same plane and the pivot point 14 is raised so as to avoid contact between the levers and the spring 11 during movement. If the spring is disposed as shown in FIG. 1, its body of greater diameter will never interfere with the work plane of the levers and the pivot point 14 can be raised relative to the lever planes only a minimum indispensable amount so as to avoid any interference with the spring rod. In this way, the whole mechanism has a reduced side bulkiness.
However, this configuration has some problems. In fact, while the side bulkiness of the mechanism is reduced, the bulkiness in depth is high because, as viewed from FIG. 1, it is necessary to take into account the spring length to which the space required for the kinematic mechanism is to be added. In addition, spring 11 works in an almost horizontal position, and therefore in a non-optimal manner with respect to the manufacturers' suggestions for this type of springs who teach to always keep the springs with the rod facing downwards to enable better lubrication of the seals. A further problem is represented by the pivot point 14 that must necessarily be located at a position that can limit maximum opening of the kinematic mechanism.
It is a general aim of the present invention to obviate the above mentioned drawbacks by providing an innovative parallelogram hinge for vertical-movement doors which has a reduced bulkiness in depth at the inside of the piece of furniture. Further aims consist in enabling better operation of the balancing spring and avoiding inappropriate limitations to the maximum opening.